1. Technical Field of the Invention
This invention relates generally to communication systems and more particularly to Voice over Internet Protocol (VoIP) telephony and to Public Switched Telephone Network (PSTN) telephony.
2. Description of Related Art
Voice telephony has been known for many years. Initially, dedicated conductors between telephones supported voice telephony. Then, operators manually switching connectors to create and tear down circuits between telephones enabled voice telephony. As technology advanced, mechanical components performed the switching operations to create and tear down circuits between telephones. With advancing technology, computers and semiconductor components replaced the mechanical components to perform circuit-switching duties. Networks created using this circuit-switched technology are generally known as the Public Switched Telephone Network (PSTN). Generally, the PSTN provides a circuit-switched, time-divided connection between telephones.
Packet data communications, such as those supported by the Internet, differ from circuit-switched communications. With packet data communications, a source device forms a data packet, transmits the data packet to a packet data network, and based upon a destination address, e.g., Internet Protocol (IP) address of the data packet, the packet data network passes the data packet to a destination device. As the Internet and other packet data networks grew in popularity, packet switched voice telephony was developed. One common type of packet switched voice telephony is Voice over Internet Protocol (VoIP) telephony. When VoIP telephony was first introduced, the data packet transmission latency of the Internet and of other servicing networks caused the quality of VoIP telephony to be significantly worse than that of PSTN telephony. Over time, packet data transmission latency of the Internet and of other servicing packet data networks has decreased. Now, VoIP telephony provides service quality equal to or better than VoIP telephony in many cases.
Recently developed VoIP telephony applications enable computer users to establish non-toll VoIP telephone calls across the Internet. Compared to PSTN telephony VoIP telephony of this type is significantly less expensive, particularly for overseas calls. However, only a limited number of people have a computer upon which this VoIP telephony application may be loaded and have Internet access of a quality that will support the VoIP telephony application.
In order to gain some advantages of VoIP telephony but still service consumers having PSTN telephones, VoIP telephony service providers typically deploy VoIP gateways. The VoIP gateways bridge communications between the PSTN (PSTN telephony call) and the Internet-(VoIP telephony call). VoIP telephony service providers typically extract a toll for servicing a call via the VoIP gateway bridge, thus destroying in part the low cost attractiveness of VoIP telephony.
Alternatives to traditional telephone network now exist that include wireless local loop and cable modem network telephone service, for example. Cable modem network telephone service systems deploy cable modems at subscriber locations. These cable modems couple to both subscriber telephones and to a cable network. A telephone service provider deploys a head unit that couples to the cable network and to the PSTN. The combination of a cable modem, the cable network, and the head unit intercouples a subscriber's telephone to the PSTN. Due to aggregation efficiencies, the cable modem network service provider can typically provide attractive rates to the subscribers, as compared to a telephone company. However, difficulties exist with such systems due to the non-local PSTN access of telephones, e.g., 911 call servicing, that make these systems unattractive from other standpoints. Thus, a need exists for systems and methods of operations that overcome the shortcomings of these prior telephony systems.